The present invention generally relates to public water systems. More particularly, the present invention relates to a dechlorinator unit for water which is discharged from fire hydrants and the like.
Chlorine is widely used as a disinfectant by water utilities and contractors. Chlorine is present in these waters as a result of disinfection of system components, such as water mains, storage facilities, etc. or disinfection of potable water.
Periodically, chlorinated waters from potable water systems are released to the environment. This may be due, for example, to planned releases of chlorinated waters as a result from operation and maintenance activities, such as disinfection of mains, testing of hydrants, and routine flushing of distribution systems for maintenance. Activities such as water main flushing in response to higher than allowable coliform counts, taste and odor complaints from the public are other examples of releases of chlorinated waters. Such discharged chlorinated water, such as from fire hydrants, are typically done into the storm drains which go to the ocean or lakes, rivers or ponds.
However, storm waters are usually discharged into receiving streams or waters leading to streams, and eventually into lakes and/or the ocean. Although chlorine protects humans from pathogens in water, it is highly toxic to aquatic species in the receiving streams, even in relatively low concentrations. In particular, chlorine may be toxic to many species protected under the Endangered Species Act.
The United States Environmental Protection Agency has established Water Quality Criteria for total residual chlorine concentrations or free residuals permissible in receiving waters, to protect aquatic life and water quality. These concentrations are based on acute and chronic toxicity effects for aquatic life. Most states in the United States have adopted a toxicity-based criterion for the water quality as well. The state regulatory agencies require water utilities to abide by the receiving water quality criterion while discharging chlorinated waters. The permit processes used by state regulatory agencies to regulate chlorinated water discharge vary significantly from state to state. For example, California, Oregon, Washington, Nevada, Maryland and West Virginia have stringent regulatory discharge limits for chlorinated waters, in that chlorine discharge limits in all water releases into receiving streams must not exceed 0.1 mg/L (or a more stringent limit in these states). Hence, preventing chlorinated water releases from reaching receiving streams and oceans is becoming an increasingly important issue for water utilities.
Dechlorination is practiced by some water utilities during releases of chlorinated water. However, many of the devices in use are complicated in that they have movable parts and/or attached hoses and can be complicated to use and expensive to purchase and operate.
Accordingly, there is a continuing need for a water hydrant potable water chlorine neutralizing unit which is simple in design and construction so as to be simple to use and inexpensive to manufacture and purchase. The present invention fulfills these needs, and provides other related advantages.